1. Field of the Invention
The present invention refers to a device for taking samples from e.g. bio-reactors or fermentors, chemical reactors, and storage vessels and for drawing off these samples into sterile receptacles.
2. Description of the Related Art
Taking samples from cultures out of a fermentor generally is indicated whenever the process parameters e.g. pH, pO.sub.2, pCO.sub.2, temperature, viscosity, and others are insufficient for interpreting the state within the cultured cells. This is the reason the desire for a sample taking device is as old as the technique of fermentation in closed vessels. To draw off the taken probe into a sterile receptacle is always mandatory when germs occasionally present in the receptacle could contaminate the probe. Therefore devices are known in the art, e.g. from the Swiss Pat. No. 629 591.
In this mentioned patent specification, which represents the state of the art, a device is described consisting of a sampling tube, a valve--e.g. a corner valve--and a bellshaped support for the sterile receptacle. The sampling tube is fastened to an outlet in the fermentor by means of a thread or by a flange. From the opened corner valve the culture broth flows through a first-longer-needle, which penetrates the elastomeric stopper of the sterile receptacle, into this said receptacle. The air contained within the receptacle is vented through a second-shorter-needle, which as well penetrates the said stopper. The difficulties of this and similar devices are encountered with their sterilization in a threefold way:
If one is assuming that the insides of the sampling tube, of the corner valve, and of the longer needle have been sterilized together with the fermentor before the fermentation has been started, sterility cannot be guaranteed, because the outside of the stopper is exposed to the non sterile air of the laboratory.
After the first sample has been taken and the receptable has been removed, the needle and the corner valve as well as the valve seat are not sterile any more and also cannot be sterilized any more.
Furthermore the sampling tube generally is contaminated with remainders of the culture broth. In case pathogenic cultures have been cultured in the fermentor germs enter the laboratory as soon as the receptacle is taken off the needle.
Other known devices work with a cup being put on to the needle during sterilization by steam and being taken away after sterilization is terminated. All the same, contamination of the sample and of the laboratory remains possible.